The present invention relates to devices for manipulating ferromagnetic objects, and more particularly to a magnetic load gripping device which can be used to lift or lower workpieces, to hold workpieces at a desired level or in a desired orientation, to transport workpieces between two or more different locations and/or to otherwise manipulate ferromagnetic commodities. Still more particularly, the invention relates to magnetic lifting and/or gripping devices of the type wherein a permanent magnet can attract a load in the event of failure of an electromagnet.
It is already known to combine permanent magnets and d-c electromagnets into load gripping, lifting or like devices. A drawback of such conventional devices is that, even though the permanent magnet is capable of attracting a load when the connection between the electromagnet and the energy source is interrupted and/or in the event of failure of the energy source, the permanent magnet cannot be disengaged from the load by remote control, i.e., if the electromagnet is inactive, the load continues to adhere to the permanent magnet.